The present invention relates to an electrical switch that can, particularly but not exclusively, perform a changeover switching action.
Electrical slide switches and changeover switches are of course widely known. In general, slide switches incorporate a sliding actuator for operation, and changeover switches are for rearranging the connection in an electrical circuit for example to reverse the direction of an electric motor.
Changeover switches for this purpose, such as those used in a ceiling fan, are often implemented by a slide switch. In a typical construction, the slide switch has six terminals arranged in two rows of three, and the two pairs of diagonally opposite terminals are each externally short-circuited, thereby resulting in a set of four terminals, as is normally required, for changeover connection/switching.
The use of a slide switch of this type for changeover connection is not ideal as two out of the six terminals are wasted. This does not only have an adverse effect on the production cost and physical size of the switch, but also introduces complication to the use and connection of the switch or a burden to productivity.
In another aspect, slide switches usually have a number of stable switching positions that are defined by resilient means co-acting between the switch body and an actuator. Such means typically take the form of a plunger biassed by a compression coil spring to bear against a wavy track, along which the plunger is slidable. Such a spring action often interferes with the contact making/breaking between the switch contacts, whereby the performance of the switch, especially during switching, may be affected in terms of, for example, contact pressure and user""s feel of switching.
The present invention seeks to obviate or to at least alleviate such shortcomings by providing an improved electrical switch.
According to a first aspect of the invention, there is provided an electrical slide switch comprising a housing, a plurality of fixed contacts located in the housing, and a switching member supported in the housing for limited reciprocating rotary movement about an axis. At least one moving contact is supported by the switching member for movement to come into and out of contact with the fixed contacts. Also included is an actuator supported by the housing for sliding movement to move the switching member.
Preferably, the actuator is supported for substantially linear sliding movement.
It is preferred that the actuator is supported for sliding movement in a direction substantially perpendicular to the axis.
Preferably, the actuator is in engagement with the switching member through a sliding hinge connection.
It is preferred that the switching member has a substantially cylindrical body that is pivotable about the axis and includes a lateral projection engaged by the actuator.
It is further preferred that the actuator includes an aperture slidably engaging the projection.
Advantageously, the switching member has a substantially cylindrical body pivotable about the axis, and the moving contact extends over an angle exceeding 180xc2x0 round the body, thereby self-gripping the body.
In a specific construction, the switching member has a substantially cylindrical surface around the axis, and the moving contact is located in that surface and lies substantially flush therewith for smooth contact with the fixed contacts.
Specifically, the housing has opposite walls including a pair of mutually aligned recesses, and the switching member has opposite ends slotted into the recesses respectively, whereby the switching member is supported.
In a preferred embodiment, the electrical slide switch includes four said fixed contacts, with two on one side and the other two on the opposite side of the switching member, and includes two said moving contacts supported on the switching member. Each moving contact has a first part for electrically inter-connecting a respective pair of the fixed contacts on opposite sides of the switching member in a first position and includes a second part for electrically inter-connecting a respective pair of the fixed contacts on the same side of the switching member in a second position.
More preferably, the switching member has a substantially cylindrical body having opposite ends and pivotable about the axis, and the first part of each moving contact extends partially around the body and the second part extends from one end to the opposite end of the body.
Further more preferably, the two parts of each moving contact together are substantially T-shaped.
In a specific construction, each fixed contact comprises a resiliently deformable strip having a first end for contact with the moving contact and a second end for connection with an electrical cable. The second end is folded back in to form a clamp with an adjacent part of the strip for automatically clamping an end of said cable upon entry.
More specifically, the contact strip has a generally right-angled triangular configuration, having an inclined upper section including the first end, a lower section including the second end, and a middle section including the said part.
In a preferred embodiment, the housing has a part engaging the actuator, and one of the actuator and housing part includes a protuberance and the other of the actuator and housing part includes a series of indentations. The protuberance is slidably engageable selectively with the indentations by virtue of resilience to define respective distinct stable positions of the actuator.
More preferably, the protuberance is engageable with the indentations in a direction that is substantially perpendicular to the direction in which the moving contact contacts the fixed contacts.
Further more preferably, the moving contact contacts the fixed contacts substantially along an imaginary vertical plane, and the protuberance is engageable with the indentations in a substantially horizontal direction.
It is preferred that the actuator includes two said protuberances on opposite sides, and the housing part includes two said series of indentations on opposite sides for selective engagement by the corresponding protuberances.
More preferably, the housing part has a pair of depending flanges each including on its inner side the corresponding series of indentations.
It is preferred that the protuberance is resiliently biassed into engagement selectively with the series of indentations.
It is further preferred that the protuberance comprises a free end of a finger that is resiliently deflectable.
It is further preferred that the actuator includes two said fingers on opposite sides and extending in opposite directions therealong.
According to a second aspect of the invention, there is provided an electrical switch comprising a housing, a switching member supported in the housing for reciprocating movement, and four fixed contacts located in the housing with two adjacent one side and the other two adjacent the opposite side of the switching member. Two moving contact means are supported by the switching member for movement to come into and out of contact with the fixed contacts. Also included is an actuator supported by the housing for sliding movement to move the switching member. Each moving contact means has a first part for electrically inter-connecting a respective pair of the fixed contacts on opposite sides of the switching member in a first position and includes a second part for electrically inter-connecting a respective pair of the fixed contacts on the same side of the switching member in a second position.
Preferably, the switching member is supported for limited reciprocating rotary movement about an axis.
Preferably, the actuator is supported for substantially linear sliding movement.
According to a third aspect of the invention, there is provided an electrical switch comprising a housing, a plurality of fixed contacts located in the housing, and a switching member supported in the housing for reciprocating movement. At least one moving contact is movable by the switching member to come into and out of contact with the fixed contacts in a first direction. Also included is an actuator, supported by the housing for sliding movement to move the switching member, the housing having a part engaging the actuator. One of the actuator and housing part includes a protuberance and the other of the actuator and housing part includes a series of indentations. The protuberance is slidably engageable selectively with the indentations by virtue of resilience to define respective distinct stable positions of the actuator. The protuberance is engageable with the indentations in a second direction that is substantially perpendicular to the first direction.
Preferably, the protuberance is engageable with the indentations in a direction that is substantially perpendicular to the direction in which the moving contact contacts the fixed contacts.
More preferably, the moving contact contacts the fixed contacts substantially along an imaginary vertical plane, and the protuberance is engageable with the indentations in a substantially horizontal direction.
It is preferred that the actuator includes two said protuberances on opposite sides, and the housing part includes two said series of indentations on opposite sides for selective engagement by the corresponding protuberances.
It is further preferred that the housing part has a pair of depending flanges each including on its inner side the corresponding series of indentations.
Preferably, the protuberance is resiliently biassed into engagement selectively with the series of indentations.
More preferably, the protuberance comprises a free end of a finger that is resiliently deflectable.
Further more preferably, the actuator includes two said fingers on opposite sides and extending in opposite directions therealong.